The present invention is directed to linear thrusters and, more particularly, to fluid operated linear thrusters which are significantly stronger yet more compact than the prior linear thrusters.
A wide variety of fluid operated linear thrusters have been available in the past. These have been employed for example for the positioning of work pieces or tools on production lines. These prior linear thrusters typically are non-rotatable and include a fluid operated piston and cylinder which moves a tool plate back and forth in a linear reciprocating fashion, and a pair of spaced shafts which are supported by linear slide bearings, and which stabilize the thruster against rotation and strengthen it against side forces and moments during operation. Although the prior linear thrusters have performed adequately well in the many applications in which they have been used, their usefulness is somewhat limited by the maximum side loads, moments and deflection to which they may be subjected during use, particularly at their maximum stroke. The maximum loads and moments that can be accommodated by the prior linear thrusters rapidly decrease in magnitude as the stroke length of the linear thrusters increases. Thus, either the loads, moments and/or deflections must be limited for a given sized and stroke linear thruster, and if greater loads, moments or deflections must be accommodated, the size, bulkiness and volumetric space requirements of the prior linear thrusters must also be substantially increased.
It has been discovered that deflection can be substantially decreased and maximum side loads and moments can be substantially increased simply and easily by a linear thruster incorporating the principles of the present invention, while at the same time reducing the complexity and expense of the linear thrusters of the present invention. Moreover, "pinch points" which frequently existed in the typical prior linear thruster constructions, i.e. locations between which human body parts may be caught or pinched as the parts of the thruster move relative to each other, can be essentially eliminated in the linear thrusters incorporating the principles of the present invention. Significantly, the volumetric space requirements of the linear thrusters of the present invention also may be substantially and considerably reduced over the requirements of the prior linear thrusters, thereby permitting substantial miniaturization and increased compactness of systems incorporating the linear thrusters of the present invention. The linear thrusters of the invention are also receptive to the internal placement of many of the components which were previously mounted externally of the thruster, and all of the fittings for the operating fluid as well as for introducing energy to the tool or tools on the distal end of the thruster may be positioned at one end of the thruster to further facilitate increased volumetric space efficiency and compactness. Moreover, the linear thruster incorporating the principles of the invention may be readily adapted for clean room applications.
In one principal aspect of the present invention, a fluid operated linear thruster comprises a guide beam having an elongate passage therein defined by internal walls in the guide beam, and a load beam positioned in the passage of the guide beam for reciprocation therein. The load beam has an outer wall which is sized and shaped so as to be supported and guided at least at two spaced locations on the internal walls of the guide beam during reciprocation of the load beam in the passage of the guide beam, and at least one of the aforementioned passage of the load beam and/or outer wall of the load beam is multisided in cross-section. A mounting is located on the load beam to mount a load on the load beam for movement with the reciprocating load beam. A piston is located in the load beam and a fluid inlet communicates a source of fluid under pressure to at least one side of the piston to urge the load beam to reciprocally move in the passage between a first position and a second position while being supported and guided by the aforementioned at least two spaced locations.
In another principal aspect of the present invention, both the passage in the guide beam and the outer wall of the load beam are multisided in cross-section, and preferably square in cross-section.
In still another principal aspect of the present invention, the passage in the guide beam is multisided in cross-section, and the outer wall of the load beam is substantially circular cross-section.
In still another principal aspect of the present invention, the load beam is located substantially within the guide beam when it is in its first position, the guide beam has first and second opposite ends, and the load beam extends from the first end of the guide beam when the load beam is in its aforementioned second position.
In still another principal aspect of the present invention, a cylinder is positioned in the load beam, and the cylinder has the aforementioned piston therein and is mounted to the second end of the guide beam, and a piston rod is on the piston and mounted to the load beam to move the load beam between the first and second positions.
In still another principal aspect of the present invention, the fluid inlet includes at least first and second fluid inlets to communicate a source of fluid under pressure to opposite sides of the piston to urge the load beam in opposite directions, and both the first and second fluid inlets are positioned on the guide beam adjacent the second end of the guide beam.
In still another principal aspect of the present invention, an energy input is located on the guide beam adjacent its second end, and the energy is communicated between the energy input and the aforementioned mounting and within the passage of the guide beam to communicate the energy from the energy input to the mounting when the load beam is in its second position and in which it is extended from the guide beam.
In still another principal aspect of the present invention, the aforementioned energy may be fluid under pressure and/or electrical.
In still another principal aspect of the present invention, at least one channel may be formed on the exterior of the guide beam, and a fastening may engage the channel for mounting the linear thruster to a base.
In still another principal aspect of the present invention, the guide beam includes a vent to vent the passage of the guide beam to the exterior of the guide beam, and the vent may be a vacuum line.
These and other objects, features and advantages of the present invention will be more clearly understood through a consideration of the following detailed description.